/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.streaming.api.graph;

import org.apache.flink.annotation.Internal;
import org.apache.flink.api.dag.Transformation;
import org.apache.flink.streaming.util.graph.StreamGraphUtils;

import java.util.Collection;

import static org.apache.flink.util.Preconditions.checkNotNull;

/**
 * A base class for all {@link TransformationTranslator TransformationTranslators} who translate
 * {@link Transformation Transformations} that have a single operator in their runtime implementation.
 * These include most of the currently supported operations.
 *
 * @param <OUT> The type of the output elements of the transformation being translated.
 * @param <T> The type of transformation being translated.
 */
@Internal
public abstract class SimpleTransformationTranslator<OUT, T extends Transformation<OUT>>
		implements TransformationTranslator<OUT, T> {

	@Override
	public Collection<Integer> translateForBatch(final T transformation, final Context context) {
		checkNotNull(transformation);
		checkNotNull(context);

		final Collection<Integer> transformedIds =
				translateForBatchInternal(transformation, context);
		configure(transformation, context);

		return transformedIds;
	}

	@Override
	public Collection<Integer> translateForStreaming(final T transformation, final Context context) {
		checkNotNull(transformation);
		checkNotNull(context);

		final Collection<Integer> transformedIds =
				translateForStreamingInternal(transformation, context);
		configure(transformation, context);

		return transformedIds;
	}

	/**
	 * Translates a given {@link Transformation} to its runtime implementation for BATCH-style execution.
	 *
	 * @param transformation The transformation to be translated.
	 * @param context The translation context.
	 * @return The ids of the "last" {@link StreamNode StreamNodes} in the transformation graph corresponding
	 * to this transformation. These will be the nodes that a potential following transformation will need to
	 * connect to.
	 */
	protected abstract Collection<Integer> translateForBatchInternal(final T transformation, final Context context);

	/**
	 * Translates a given {@link Transformation} to its runtime implementation for STREAMING-style execution.
	 *
	 * @param transformation The transformation to be translated.
	 * @param context The translation context.
	 * @return The ids of the "last" {@link StreamNode StreamNodes} in the transformation graph corresponding
	 * to this transformation. These will be the nodes that a potential following transformation will need to
	 * connect to.
	 */
	protected abstract Collection<Integer> translateForStreamingInternal(final T transformation, final Context context);

	private void configure(final T transformation, final Context context) {
		final StreamGraph streamGraph = context.getStreamGraph();
		final int transformationId = transformation.getId();

		StreamGraphUtils.configureBufferTimeout(
				streamGraph,
				transformationId,
				transformation,
				context.getDefaultBufferTimeout());

		if (transformation.getUid() != null) {
			streamGraph.setTransformationUID(transformationId, transformation.getUid());
		}
		if (transformation.getUserProvidedNodeHash() != null) {
			streamGraph.setTransformationUserHash(
					transformationId,
					transformation.getUserProvidedNodeHash());
		}

		StreamGraphUtils.validateTransformationUid(streamGraph, transformation);

		if (transformation.getMinResources() != null && transformation.getPreferredResources() != null) {
			streamGraph.setResources(transformationId, transformation.getMinResources(), transformation.getPreferredResources());
		}

		final StreamNode streamNode = streamGraph.getStreamNode(transformationId);
		if (streamNode != null
				&& streamNode.getManagedMemoryOperatorScopeUseCaseWeights().isEmpty()
				&& streamNode.getManagedMemorySlotScopeUseCases().isEmpty()) {
			streamNode.setManagedMemoryUseCaseWeights(
					transformation.getManagedMemoryOperatorScopeUseCaseWeights(),
					transformation.getManagedMemorySlotScopeUseCases());
		}
	}
}
